Let's take a moment to inflect.
Um, I might need your other blog's powers.
Standpipe has a well-concealed point.
"I guess U(t) and it's derivatives is coming closer to zero or evening out."
+0 points.
Oh, wait, total unemployment is the area under U(t). If the rate at which unemployment is rising was staying constant, that would mean U(t) = a for constant a. If the rate at which unemployment is rising is slowing down, U(t) is everywhere (that we care about) positive, but has negative slope at the most recently measured t. U'(t) is everywhere (that we care about) negative. Finally, U''(t) is your mom.
What can you say about U(t) and its derivatives?
The Austin campus has its charms, but most of those are derivative of Austin itself, and the sea of burnt orange is an eye sore. UTEP has that inspiring basketball story, and San Antonio seems to be on the up.
7: Except that it was known as Texas Western when it happened.
Come on, Criminally, let's be serious.
UTEP has interesting architecture too.
5: you should deduct a point for misuse of "it's". I know it's a math class, but standards should be enforced uniformly.
What can you say about U(t) and its derivatives?
Avoid the bell tower tranche.
11: Subject-verb agreement too. It's wrong in so many ways!
6 gets some points for good effort, but not all the points for being inaccurate.
Was it () who the other day who mentioned that some of us among the Unfoggedtariat don't know about derivatives, because we never had Calculus? Yeah, that question and two thumbs gets you: This Guy.
This sentence
Jo/di Chap/man clicked on a Twitter message last month to take an online intelligence test, causing her own account to be hijacked.
http://www.nytimes.com/2009/12/14/technology/internet/14virus.html?em
really just made my day.
although i think i'm sad that in the googlebookcrome amazonmp3kindal iphonefacebooklife future, we'll have to pay for everything, instead of enjoying the thrill of getting away with things. life shouldn't be so precious. promiscous contact with art lets you be more honest about how you like something
whoever pays attention to the syntax of things
will never wholly give you bonus points
isn't the interestnig question about change in u5, wages, per education cohort, et al against u(t)?
but not all the points for being inaccurate.
Damn, I hate leaving inaccuracy points on the table.
actually kinda topical: i had a 'this is your college major/department (econ) wanting to know how well we did' email about a month ago, i was kinda bitchy about too much chicago school and not enough maths in my response
It has a positive second derivative, which, according to Republican economists, means that now is a perfect time for a capital gains tax cut.
You can't say anything, because you don't know how many people have gotten jobs or stopped looking in the past month.
Is it a trick question because U(t) is discontinuous? Because that would be cute.
"(Some correct stuff.) This means f(x) is increasing because f'(x) is increasing but f''(x) is slowing down positively because acceleration is slowing down. We are probably approaching a local max in unemployment."
+2 for the correct parts. Some stuff crossed out.
It is a trick question in part, in that the unemployment rate is a percentage of the workforce, and not a rate the way a derivative of a function is a rate.
Anyway, it could be that the unemployment rate is increasing more slowly because lots of the unemployed are dying. That could be the case regardless of how it is with U(t).
So this is a post about unemployment involving math? It's like heebie wants us to off ourselves.
It has a positive second derivative,
Right!
which, according to Republican economists, means that now is a perfect time for a capital gains tax cut.
I thought any second derivative was a good time for a capital gains tax cut according to them?
I desire to know why you can infer anything about the function or its derivatives in light of considerations such as those advanced in 25.
Also, presumably if you meant the rate was decreasing, you would have said that -- so what does does "the rate is slowing down" mean?
28 and 25: It is a trick question in part, in that the unemployment rate is a percentage of the workforce, and not a rate the way a derivative of a function is a rate.
Sure, but the question clarifies what exactly we're going to be calling our function, and what it's rate of change is, because I called U(t) the raw data about job loss. You can get back and forth between U(t) and the unemployment rate pretty easily.
30: the rate at which unemployment is rising is slowing down. Unemployment is still increasing.
You can get back and forth between U(t) and the unemployment rate pretty easily.
So suppose U(t) = 5000—every month 5000 people get fired. Surely E(t)—the number of people who get hired in a month—will affect what the unemployment rate is? If E(t) is 5000, or 10000 (in a given range), or 0, that makes a difference!
36: That would turn it into a differential equations problem, which would really be jerky of me to give to a Cal 1 class.
"Suppose the total employers highering in US is 5000t^4, with t being total number of applicants, so U(t) = 5000t^2/12, where 12 stands for the # of months. U'(t) = (blah, blah). Henceforth, either the total number of job offers needs to go up, or the total # of applicants needs to go up."
+0 pts but great conclusion.
It was also jerky of you to give an unanswerable problem to a Calc 1 class! When you hear a report that the rate at which unemployment is rising is slowing down, you can't infer that this is because fewer people are losing their jobs.
It's like he's decided to just start baiting you personally, neb.
It has a positive first derivative (it's still increasing) but a negative second one (because it's increasing more slowly)?
Was it () who the other day who mentioned that some of us among the Unfoggedtariat don't know about derivatives, because we never had Calculus?
Yep, that was me. Thanks for the remedial thread, Stanley.
ASSUMING that all changes in unemployment can be chalked up to job loss!!!!
Neb, I feel like this is an emotional area for you. Is there something you'd like to share with the group?
He's just upset because the president of physics didn't reply to his e-mail.
43: Incorrect.
U(t) as you've defined it isn't unemployment, U(t) is (ignoring all of the considerations nosflow brings up) the derivative of unemployment. So U(t) doesn't have positive first derivative and negative second derivative. U(t) is itself positive, with negative first derivative. Just like Standpipe says in comment #6.
Trick question! You can't say anything about unemployment, because you don't know how many people are getting jobs.
pwned multiple times by Ben.
If u(t) actually was unemployment, wouldn't the function be positive but the first derivative negative, since it is still increasing but at a slower rate?
I don't see why Standpipe wasn't exactly right at the beginning. Especially about your mom.
But I don't trust my basic math skills at the moment, having just triple-checked a calculation and found nothing wrong with it, but having four published papers in front of me that got a different result.
Yeah, if u(t) were the unemployment rate itself, then if the rate at which it's rising is dropping, it would have a positive first and negative second derivative. But it isn't the unemployment rate.
There seems to be some ambiguity about the way the function is being defined.
"U(t) is the number of people that lose their jobs each month".
To continue flogging the expired horse, I thought heebie's intent, based on "U(t) is the number of people that lose their jobs each month", was for U(t) to be the derivative of the total unemployment. In which case "unemployment is rising" means U(t) > 0 and "the rate at which unemployment is rising is slowing down" means U'(t) < 0. Which is what Standpipe said way back in 6.
On the other hand, "U(t)" is a really nasty name to give "the time derivative of unemployment" if you're not trying to be evil and confuse people.
Basically, it sounds like heebie intended for U(t) to be the unemployment rate as per 56, but the way she defined it in the problem (probably to make it easier for her students to understand) is making people interpret it differently and come up with different answers.
Another way to put it is that the way she defined it in the problem is making people interpret it accurately.
"The way she defined it in the problem" being the part quoted in 58, of course.
(1) Combine 6 and 7 which are orthogonal, yielding a saddlepoint.
(2) What can you say about U(t) and its derivatives? There's no requirement to be germaine, right ?
U(t) will lose, its derivatives will win.
Suppose the definition had been phrased thus: "Suppose U(t) is the unemployment rate."
Then the question would be answerable and would have the answer heebie asserts it to have.
But of course the students aren't able to know that heebie thinks that the answer should be such-and-such and interpret the problem on that basis. Given what it says in the actual problem statement, it's either unanswerable (on nosflowian considerations) or it has a different answer. One can't rule out that the prof has posed a trick question, after all, especially if it's a bonus.
Has anyone mentioned the Peter Watts beating and detention at the border crossing around here?
Then the question would be answerable and would have the answer heebie asserts it to have.
Right. Which implies that heebie, who wrote the test and is grading it, intended the definition she gave to be equivalent to the definition in 65, as does everything else about the phrasing of the question, specifically the mention of the unemployment rate in the first sentence and the plural "derivatives" in the last.
67: I would tell you, but bob might attack me.
Good to see that neb is channeling every student I ever hated (because my perfect problem was posed poorly and failed to give the result I thought it should).
FUCK YOU PARANOID ANDROID. FUCK YOU. STOP MOCKING US.
I'm sure that she intended that definition, but that's irrelevant. You can only answer the question that's actually been posed. (Surely if B were still around she'd have said something about the intentional fallacy by now.) Nothing about the plurality of "derivatives" indicates that that's the definition she intended, nor does the fact that she mentions the unemployment rate. It's not as if the number of people who lose their jobs in a month has nothing to do with the unemployment rate!
Surely the way the problem is defined makes the function discontinuous. "Number of people who lost their jobs in the month" isn't an abstract continuous quantity, it's discrete and only has a value/changes once a month. So it has zero derivatives, justifying the plural. Or the derivatives are zero everywhere they're defined.
73: Could be a one-month moving average. (These calculus students know what a moving average is, right...?)
I'm sure that she intended that definition, but that's irrelevant.
Okay, well, as long as we're in agreement about what actually happened here my work is done and I'm going to bed. I don't really care about the rest of it.
I thought about that, but all it really does is introduce more discontinuities.
These calculus students know what a moving average is, right...?
I'm acting from the assumption that these students know nothing that was not either taught in the course or explicitly defined in the test. Like, say, what "the unemployment rate" means.
We might not have agreed yet!
I'm pretty sure we have, but if you know of any outstanding disagreements please point them out. It's getting late and I have a paper to turn in by noon.
I thought about that, but all it really does is introduce more discontinuities.
Why can't it be continuous? (Ignore, for the moment, the discreteness of 'people'.)
heebie's going to be pissed when she checks on this thread in the morning and sees how it turned out.
I should probably sleep. Waiting for cow-orkers to reply to my email is probably a lost cause this late at night.
I'm acting from the assumption that these students know nothing that was not either taught in the course or explicitly defined in the test. Like, say, what "the unemployment rate" means.
In that case it's even worse since "the unemployment rate" isn't given a definition in the test (and presumably wasn't taught in the course). Adjacency isn't definition.
Adjacency isn't definition.
It's close enough.
Multiple people can lose their jobs simultaneously. Even if you ignore the discreteness of people that makes a jump in the function when it moves in or out of the average.
I mean, if they don't know what it means, and they can't determine it from the wording of the question, they're pretty much stuck, aren't they? Which isn't necessarily a problem, since it's a bonus question, but come on.
I'm sure there's at least one xkcd addressing this sort of thing, but I'm not going to bother looking for it.
71: I don't really read here anymore, and I didn't see a post on it.
And now I really am going to bed. Good night, everyone.
As a student, this would have sent me into a nosflowian tizzy of confusion (sincere confusion, not being a smartass) about what I was allowed to assume about the relationship between "the unemployment rate" and "the number of people who lose their jobs each month". I probably would have resolved it by writing a plaintive/pissy note before the problem saying "Unless U(t) is the first derivative of the unemployment rate, I can't do the problem. So I'm going to assume that's true. But I don't get it."
92: PERHAPS A CAREER IN LAW WOULD BE MORE SUITED TO YOUR DISPOSITION.
I've mentioned before, I marked an entrance exam where the Economics prof had set a problem where the students had to calculate how many bee hives they could build in a piece of land. Like every other person, except for the Prof and one student [out of about 90], I solved it algebraically and assumed the answer was to be an integer.
The Prof however, solved it using calculus, and gave an answer to three decimal places. So much the worse for the Prof.
(and I would have gotten Standpipe's answer. I'm still unsure how I should have interpreted the problem to get any answer other than Standpipe's.)
Wait, wait, I know! I haven't read the thread, and I'm sure someone else has already posted the right answer. I just want to register my right answer.
U(t) and its first derivative are positive and the second derivative is negative.
Right? Remember, the only calculus I ever took was reading Newton.
Ok, I was interpreting U(t) as the unemployment rate, not as the change in the employment rate. The question was ambiguous on this point. The precise definition (people losing jobs that month) means that it is a derivative, but all the contextual clues say it is the unemployment rate itself. I say it is a Prof Fail.
My problem is that I don't know what "positive" and "negative" map out to in this context. I thought that if something was slowing, the appropriate derivative would be negative (negative = going down.) But maybe the derivative is just a scalar, so that if change is occurring in any direction, the derivative is positive? I'm confused and hope someone returns to this thread.
100 people lose their jobs!
nosflovian
nosfluvial.
101: The nurse just made me fill one of those.
Mo MacArbie, Mo MacArbie, Mo MacArbie Clementine,
You are lost and gone forever, Mo MacArbie Clementine.
"The number of people losing their jobs every month" isn't the unemployment rate (which is a ratio), and it isn't even the number of people unemployed (which is affected by the number of people who lost their jobs last month but find a new job this month). It's just the number of people who lose their jobs this month.
To make the question work, I think it would be OK if u(t) was just defined as the number of unemployed people.
Don't forget "discouraged" workers leaving the pool of unemployed without finding a job.
You all are frustrating, but not Rob in 98.
Listen: U(t) is not the number of people who lose their job per month. It's not a rate. The y axis would not be labeled people/month. U(t) is the number of people who lose their job in a given month. The y axis would just be labeled plain old people. It is a quantity, not a rate of change.
You're right to think that you're so cute, HBGB.
As a button! You're not so bad yourself, Mr. Chalk.
I can see why people would find these two sentences confusing:
"U(t) is not the number of people who lose their job per month."
"It's not a rate."
Are you saying that those two sentences say opposite things? Don't they say the same thing? Or that, while consistent with each other, they are both confusing?
When you say "per" a generic unit of time, it sure as hell looks like a rate. To make it look like an absolute quantity, you should say "in" a defined period of time.
'Per month" = a rate
"in the last month" = a quantity.
It seems picky and nose-flovian, but the ability to pay attention to such details of language is one of the few useful skills I have.
When you say "per" a generic unit of time, it sure as hell looks like a rate.
If you say "per", it is a rate! I said it's NOT the number of people who lose their job per month. That's how people are misreading it.
U(t) is the raw number of people who lose their job, each month.
In other words, I think you're missing the "not" in the first quote in 109.
But it doesn't matter if it's the number of people losing their jobs per month, or in a given month; all that does is change the units you're recording it in. Either way, if unemployment is rising, it means U(t) > 0, not U'(t) > 0.
U(t) > 0 means there is a positive number of people who have lost their job this month. U(t) is presumably a positive function. U'(t) > 0 means that number is increasing.
U(t) > 0 means there is a positive number of people who have lost their job this month.
Which means that unemployment is increasing.
113: Shit, so much for my one useful skill.
Let's never put anything I do professionally under a microscope ever again.
"Poorly phrasy" sounds like a Whedony Buffy-y phrase.
Lets go back to calling each other cute. It feels a lot better than displaying our difficulties in reading and writing.
"Poorly phrasy" sounds like a Whedony Buffy-y phrase.
I almost went with "wrong", but got tangled up in that grammar somehow. Now I can't see what I had a problem with, though. I could have said "I think I'm so cute wrong" and that would have been perfectly clear.
122: But... you can't be wrong, heebie!
Next I'll find out that Judah Claus isn't real....
"Poorly phrasy" sounds like a Whedony Buffy-y phrase.
Poorly phrasy much?
Quick Santa bleg -- iPod Touch, is 8GB enough, or do I need the 32GB?
Most people are perfectly happy with 8GB. Depends on the size of your digital music collection.
How much music does this person have? 8 GB is about 65 CDs worth.
For the iPod Touch, I would go for the largest drive they have because of all the non-music apps and whatnot you can put on it. I have an iPod Nano and 8GB is plenty, even with my gigantic digital music library. That's more than I can listen to in a day, and I swap stuff on and off it frequently.
My son needed more than the 8 for the apps he likes to run.
Ah, yes, the apps. And video, if you're into tiny screens. IYKWIMAITTYD.
CC-- did 32 do? It's for Rory, and I don't want to go too overboard, but also don't want to give her sthing useless.
Thanks. And Rory will thank you, too.
All I got for Christmas was sthing useless.
My son needed more than the 8 for the apps he likes to run.
this is sad news for me. My daughter wants a touch for christmas and I was going to get her the 8 gigs.
I just replaced an ipod touch that broke with an 8GB one, because I balked at the 32GB price. I've only got a few simple apps--a to do list and grocery gadgets that syncs with an online account, and I mostly use it as a calendar, e-mail reader and for surfing the internet in coffee shops, car dealers and hospital lobbies.
In a year or two when my current verizon contract ends and data plans are cheaper I want to get an iphone.
My wife is fine with her 8. Different user profile.
My son's is 16 GB IIRC, and it's fine. He doesn't have a whole lot of music on it but he plays a lot of games.
16 GB is no longer an option. Just 8, 32, and 64.
They do that crap with cell phone minutes, too. When I was looking for a plan recently, they try to shuffle you into 200-400 minutes, or in the 1000 minutes ballpark. More or less. They discontinue packages with 600-800 minutes because they're so user-friendly.
Let's never put anything I do professionally under a microscope ever again.
Aw, Heebie. Remember: it's a hive brain.
141: So either you can buy the 32GB for the same price I paid for 16GB five months ago or my memory sucks. Or possibly both. But IIRC the options were 8GB for $249, 16GB for $299, and 32GB for $399 when my kid's birthday rolled around in July.
Rory's getting 32GB, $269 at Costco. It's a bit more than I thought I should spend. 8GB is $179, but if it goes unused because it lacks the memory to do the stuff young people do, well I'd rather spend more and be sure it has what we need. It's sort of tricky b/c UNG can't afford to get her much this year, and then I feel a bit guilty if I'm being too extravagent. But then, I am also careful with my spending so I can do stuff like this, so... I should just accept that buying children's affection is a time-honored tradition and be glad that I can buy more than he can.
What else is the money for?
(Oh, I suppose I ought to read the unicorn thread . . .)
Mine has gotten a LOT of use out of the Touch (sometimes to my chagrin). Unlike the stupid Wii, which hasn't been turned on in months.